Arsène Wenger is not the type of manager who keenly inspects the opposition searching for weaknesses, instead preferring to concentrate upon the strengths of his own players. For Arsenal's crucial trip to Newcastle United, however, there seemed an obvious area of vulnerability to exploit.

With the left-backs Ryan Taylor, Davide Santon and Massadio Haïdara unavailable through injury, the Newcastle manager, Alan Pardew, was forced to continue using the centre-back Mapou Yanga-Mbiwa in an unfamiliar left-sided role. With Arsenal's right-sided attacker Theo Walcott on target in his last three matches, their approach was predictable – try to get Walcott running in behind Yanga-Mbiwa.

The format of Arsenal's side in recent weeks, with the playmakers Tomas Rosicky and Santi Cazorla dovetailing towards the left of the pitch, means their build-up play generally originates from that flank, creating a natural angle for a diagonal pass in behind the opposition defence. This time, however, Arsenal rarely worked the ball into those positions in the first place, because their possession play was so poor. The pass completion rate of 80% was the third-worst of their Premier League season – only in games against Manchester City and West Brom, when they've played long periods with only 10 men, have they conceded possession so readily.

Arsenal's determination to find their key attacker resulted in a succession of long, straight passes from deep positions that even Walcott was unable to reach. Fabricio Coloccini played an important role to the left of Newcastle's defence, moving quickly to sweep up behind Yanga-Mbiwa, while goalkeeper Steve Harper ensured he was in a good starting position, making crucial interceptions on more than one occasion.

Yanga-Mbiwa also received protection from the defensive midfielder Cheik Tioté, and Jonás Gutiérrez, one of the Premier League's most disciplined wide players. But Yanga-Mbiwa handled the situation well – not merely because of his defensive positioning, which was intelligent throughout the game, but also because of his commitment to attack. He created the game's first goalscoring opportunity when he charged down the line unexpectedly, and with the whole of St James' Park wondering whether he was capable of crossing with his unfavoured left foot, his pull-back found Papiss Cissé, who fired over.

That was an important moment – the next time Yanga-Mbiwa pushed forward Walcott felt obliged to follow, and with Arsenal's primary attacking weapon forced deeper than he expected, the away side lacked invention. Lukas Podolski's lack of movement meant Cazorla and Rosicky had no obvious option on the rare occasions they received possession between the lines, and it was strange to see Arsenal so bereft of ideas.

In the end, Arsenal's goal originated from a set piece – and it was fitting that Laurent Koscielny scored. His return to the side after their terrible defensive performance in the 2-1 defeat at White Hart Lane was crucial to their end-of-season run to fourth. In the 10 games since, Arsenal have collected eight wins, two draws and five clean sheets, while this was their third consecutive 1-0 away win. When their attacking play has faltered, their defensive resilience has saved them. This was a perfect example.